1. Field of the Invention
This invention relates generally to techniques for electronic imaging, and relates more particularly to a system and method for effectively performing a white balance procedure for electronic cameras.
2. Description of the Background Art
Implementing effective methods for performing electronic imaging is a significant consideration for designers and manufacturers of contemporary electronic entertainment systems. However, effectively implementing imaging systems may create substantial challenges for system designers. The white balance systems provided on most cameras are very fast and convenient, and they are good enough for general use in simply recording images of many common subjects.
However they are not satisfactory for controlling the white balance of subjects that are lighter or darker than average, or of subjects consisting of one dominant color, or for close-ups in general, or with any indoor subjects, especially in mixed light conditions. While pre-set functions on current models of digital cameras may produce colors that appear natural in some lighting situations, inaccuracies are unavoidable as long as built-in image sensors continue to read through the center of the field and are programmed to reflect the assumption that there is an “average” subject, that it's subject brightness level averages to 18% gray, and the camera's color manager is dependent on the presence of something white near the center of the image in order to derive an analysis of local color.
One method of making these hand-held cameras more effective would be to place a neutral card of any value facing the camera and in the same illumination as a subject to be photographed, and filling the cameras field of view, to serve as a “standard” value in place of the camera and meter's natural variable value, in establishing exposure settings for a given scene or subject.
If such a card were of optimum value for rendering of all values in the same illumination, then it would serve to provide optimum exposure settings for the rendering of all values in any illumination. However, such a card is a cumbersome thing to carry and protect and is awkward to use, and often reflects excessive light as well as local colors due to surface glare. In addition, when working with people, it is disruptive and awkward to use in that it is almost impossible to withdraw the subject's attention from the card so as to enable taking an adequate photograph.
It is clear from the discussion above that neither the “reflectance” method nor the “incident light” method is ideally suited for use with electronic cameras equipped with through-the-lens metering facilities. In conjunction with the “reflectance” method it is obvious that the use of a gray card with a hand-held film camera equipped with through the lens metering facilities is too cumbersome and inconvenient to be used by the great majority of photographers. Use of such card for determining the proper setting of the camera in anything but a studio environment has proved awkward, inconvenient and, despite knowledge of this method, has never gained favor with hand-held camera photographers.
For at least the foregoing reasons, it is apparent that developing new techniques for implementing imaging systems is a matter of concern for related electronic technologies. Therefore, for all the foregoing reasons, developing effective systems for implementing imaging systems remains a significant consideration for designers, manufacturers, and users of contemporary electronic imaging systems.